Pioneer Valley Fern Society

A New Fern to Learn!

Miss Slosson’s Wood Fern

If you feel pretty confident identifying the common and not so common ferns in our area, you might consider the next challenge: Hybrids! There are a number of hybrid ferns. Our subject today is a Wood Fern hybrid, Miss Slosson's Wood Fern (Dryopteris x slossoniae). This one is not too hard to identify because it has a few distinctive features. Miss Slosson's Wood Fern is a combination of Marginal Wood Fern (Dryopteris marginalis) and Crested Wood Fern (Dryopteris cristata), both of which we see often and many of you can identify. Crested Wood Fern is considered an obligate wetland plant, always occurring in wetlands, while Marginal Wood Fern is almost always found in uplands. The hybrid is found in wetlands, like Crested. So what are the first distinguishing features to look for?

As with other wood ferns, they grow in nice symmetric clumps, as shown in the photo. The leaves are somewhat leathery like the Marginal Wood Fern leaves, but it is growing in a wetland. The lower pinnae or leaflets are much shorter than on Marginal Wood Fern, and more triangular, like Crested, but not as short and stubby. The sori also help in the identification. Marginal Wood Fern has sori that are up to the very edge of the margins of the pinnules or leaflets. Miss Slosson's Wood Fern has sori that are located midway between the outer edge and the midrib, similar to Crested. This fern is really a nice mix of both parents.

I love the name of Miss Slosson's Wood Fern, and wondered who the namesake was. It took a lot of googling to find anything on Miss Margaret Slosson, but she was a very interesting woman and Pteridologist. She was born in 1874, and is believed to be the first person to deliberately create a hybrid between two ferns, to prove that it could occur. In 1899, at the age of 25, Miss Slosson developed the technique and recreated the hybrid of Dryopteris marginalis and D. cristata in a lab. The Hardy Fern Foundation article (Summer 1998) I read on this described this as a "milestone in the study of the genus". She also synthesized a known hybrid of Ebony Spleenwort a few years later, identified a new hybrid of Wood Fern (Dryopteris pittsfordensis) in 1904, and published the book "How Ferns Grow" in 1906 (age 32). Miss Slosson worked with the New York Botanical Gardens and summered in Pittsford Vt, where she reported identifying 45 species and 6 varieties of ferns within a 3 mile triangle. In 1942 she was honored for her work by E. T. Wherry naming the Wood Fern hybrid she had worked on Dryopteris x slossoniae or Miss Slosson's Wood Fern.

This is an amazing year so far for the healthy abundance of ferns. Hope you are out there enjoying them!

Posted: to General News on Mon, Jul 3, 2023
Updated: Wed, Jul 5, 2023

Pioneer Valley Fern Society

321 Montague Road
Shutesbury, MA 01072